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One of the prime mission goals for NASA's brand new Mars Science Laboratory (MSL) is to search for organic compounds in Martian soil. The discovery would be a huge boon for science. Carbon-laced molecules are critical for the chemistry of life (as we know it), so if the MSL rover Curiosity's instruments detect them, another piece of the mysterious puzzle of Mars habitability will slot into place. But there's a huge caveat to this exciting hunt: The detection of organics in the Mars soil would not prove that there's life on Mars. That would be like finding a grain of flour on the floor and concluding there must be a Christmas cake in the room - you need flour to bake a cake, but it

One of the prime mission goals for NASA's brand new Mars Science Laboratory (MSL) is to search for organic compounds in Martian soil. The discovery would be a huge boon for science. Carbon-laced molecules are critical for the chemistry of life (as we know it), so if the MSL rover Curiosity's instruments detect them, another piece of the mysterious puzzle of Mars habitability will slot into place. But there's a huge caveat to this exciting hunt: The detection of organics in the Mars soil would not prove that there's life on Mars. That would be like finding a grain of flour on the floor and concluding there must be a Christmas cake in the room - you need flour to bake a cake, but it doesn't mean there is a cake.

So, it may seem baffling that, during a tour of the ULA rocket assembly plant in Alabama on Wednesday, NASA Administrator Charlie Bolden found himself having to field questions about whether NASA had discovered life on Mars. In reply, he simply said, "Not yet. We haven't found it yet."

The question about life on Mars has been asked ever since astronomers began to train their telescopes onto the small red world. In recent years, after sending an armada of satellites and surface missions to the planet, we realised that although any life form would have a hard time on the barren, cold, radiation-soaked landscape, there could be alien oases where the most basic forms of microbial life have eked out an existence. The hunt for any kind of extraterrestrial life is one of the most profound searches in human history and could, ultimately, help us understand our place in the galaxy.

One for the history books

With the help of missions that have gone before Curiosity, we know that Mars was once a wet world with liquid water oceans that tell the story of an ancient Mars that was much warmer than it is today. So the next logical step is to look for the chemicals that form the backbone of biology - does Mars have organic molecules in its soil and rock that could form the basis of a hypothetical Martian organism? To make a Christmas cake, you need more than just a grain of flour - where's the eggs, fruit, icing and oven to bake it all together? The cake analogy is close to what Mars scientists are trying to achieve - they know the temperature was once right for liquid water to exist, so where's the proverbial "flour" of the mix?

Inside Story - What will Curiosity tell us about Mars?

This is where Curiosity's organics-hunting instruments come in. But only four months into the mission, has the six-wheeled rover already hit pay dirt? According to an NPR article published on November 20, there has been some excitement amongst mission scientists who think they've discovered something "historic".

"We're getting data from (Sample Analysis at Mars instrument) as we sit here and speak, and the data looks really interesting," John Grotzinger, MSL principal investigator, told NPR reporter Joe Palca during a visit to NASA's Jet Propulsion Laboratory in Pasadena, California. "The science team is busily chewing away on it as it comes down." And then Grotzinger said the now infamous line: "This data is gonna be one for the history books. It's looking really good."

Naturally, when a lead scientist starts talking about making history, something big must be in the offing. Predictably, the media reacted. As the Sample Analysis at Mars (SAM) instrument is looking for organic compounds in Mars soil, it didn't take long for speculation about organics to run riot. The rumours spread, probably helped by the fact that an obviously-excited Grotzinger stopped himself from totally spilling the beans as to the nature of the data he was analysing. All we know was that the data was coming from SAM, and SAM is responsible for seeking organics. To anyone outside of the mission team, that conclusion seemed obvious.

In response to the media speculation, NASA tried to put the breaks on. When replying to questions from Universe Today writer Ken Kremer, NASA spokesman Guy Webster said, "As for history books, the whole mission is for the history books. John was delighted about the quality and range of information coming in from SAM during the day a reporter happened to be sitting in John's office last week. He has been similarly delighted by results at other points during the mission so far."

In a nutshell: It's one "for the history books" because the whole mission is "for the history books" (and John Grotzinger is always this excited).

One for the cookbooks

As an additional measure to stem the ever-rising tide of speculation, NASA thought it necessary to issue a press statement on November 29, saying: "Rumors and speculation that there are major new findings from the mission at this early stage are incorrect... At this point in the mission, the instruments on the rover have not detected any definitive evidence of Martian organics." The statement also said that there would be no major announcement about organics on December 3 at the AGU conference in San Francisco.

So although all indications were that Curiosity had discovered organics, it is too early to reach any conclusions. More work and analysis is needed and proper science needs to be carried out.

It can be hard for science to be properly communicated to the media and public. In this age of rapid communications and increased connectivity, the scientific process can seem slow, laborious and secretive. But to do science right, no grand announcements should be made until the process has seen its course. Data needs to be collected, analysed, re-analysed and compared to models. Only then can theories form and conclusions be arrived at. Whether or not Curiosity's SAM instrument has detected organics at this early stage is almost irrelevant, the scientific process is in mid-flow. But in a publicly-funded space agency there is pressure to keep the process as open as possible, there are some profound scientific studies that cannot (and should not) be shared before the final results are in.

It is worth remembering that although SAM is looking for organics in Mars soil, that's not its only job. The media's attention (mine included) grabbed onto organics as being the source of the excitement. But that natural instinct blinkered us from considering what else SAM may have detected. The same instrument was used to "sniff" the Mars air and, earlier this month, MSL scientists announced the surprising lack of methane detected. Previous observations from Earth and from Mars orbit have detected a global distribution of seasonally-fluctuating quantities of methane - a factor that is surprising as the gas is short-lived and only has two realistic production mechanisms, one of which is through metabolising microbes. Mars also seems to have a rapid methane destruction-production cycle and microbes could be at the root of it all.

What if Grotzinger's excitement focuses on follow-up SAM atmosphere measurements? What if, after further tests, methane has been detected? That would be fascinating; extremely localised methane detection could indicate that there are pockets of methane production... or perhaps a change in wind direction changes the concentration of the gas in the air?

There's more than one way to find evidence of microbial life, so it's worth keeping that in mind when the media focuses on the hypothetical discovery of that one grain of flour, in actuality, Curiosity could potentially smell the cake in the oven.

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